MAKYLA.NJ) (ii;()l-()(ll('AL SLKN'l'A' 215 



inch. Cellules arranged in longitudinal linos and usually in quincunx. 

 About six tu ten rows oji each side of tlie l)ranches. although we have in 

 one case coimlcd tucnly just hclow a l)irurcatioii. Ccllides closely jux- 

 taposed; eh)ngated oval atilcrioily. ((Hil I'acttMl and afterwards dilated 

 posteriorly, and straight or slightly eiiiarginate at the proximal edge. 

 Opening elongated oval, varialjle in form and size, occasionally suh- 

 quadrate, sometimes slightly narrowed posteriorly, cither more or less 

 than half the surface of the cellule, no lip or margin, simply ])iei'ccd in 

 the substance of the cellular wall and placed at the lowest part of the 

 surface. Surface smooth, concave, elevated at the anterior and antero- 

 lateral margins into a rounded or acute edge, a little higher than the 

 posterior of the surface of the adjoining cellules. Fi'om this edge the 

 surface slopes in^vards toward the mouth. Behind the mouth the sur- 

 face is generally marked by two radiating depressed lines, running from 

 the proximal corners of the mouth to the corresponding corners of the 

 cellule, between Avhicli is a rounded elevation, not as high, however, as 

 the anterior end of the preceding cellule. 



The accessory cells [vicarious avicularia] appear to be ordinary cellules 

 undeveloped, and are not always placed immediately in advance of an 

 ordinary cellule. They are about two-thirds of the ordinary size, not 

 closed above, by a testaceous covering, but have the anterior edge very 

 much produced, thin and overhanging, and about as high as the length 

 of the aperture. We have noticed but one broken ovarian vesicle, which 

 is placed in advance of the cellule to which it belongs, appears to have 

 been semiglobular and overlaps the proximal surface of the succeeding 

 cellule, reaching to the edge of the aperture." Gabb and Horn, 1862. 



Although rather variable this is still to be counted as an easily recog- 

 nized species. Ooecia occur but rarelj^, only four or five specimens out 

 of fifty or more in my collection having any at all. They are cucullate, 

 often with a delicate longitudinal ridge across them and about as large 

 as in Membranipora spicidosa, but more uniformly convex. The species 

 occurs in the Upper Cretaceous at Mullica Hill, Timber Creek, and 

 Vincentown, IST. J. 



Occurrence. — iVquiA FoEiiATiON". Upper Marlboro. 



Collection. — Maryland Geological Survey. 



